1. Field of the Invention
The present invention relates to heat-retaining exhaust components and methods of preparing such components. More particularly, the present invention relates to a method of lining a two-piece exhaust pipe or an automotive cylinder head with a heat-resistant compound containing zirconium, a ceramic material, or both, and a heat-retaining component which is the product of the described process.
2. Prior Art
In the automotive industry, it has long been recognized that heat generated by the combustion process emanating from hot vehicle components into the engine compartment of a vehicle is a problem. Not only does such heat degrade the various other components in the engine compartment which are not heat resistant, but the heat also causes the hot components themselves to become brittle and deteriorate. The problem is exacerbated in today's smaller engine compartments since cars are being "down-sized", especially when a high-performance engine such as a turbocharged or supercharged engine is packed tightly into such a small engine compartment. Heat generation in engine compartments is not limited to such high-performance engines, however. Heat loss is particularly a problem with any component which comes into contact with hot engine exhaust, such as vehicle cylinder heads, exhaust manifolds, and exhaust piping.
Many varied types of heat shields and insulation have been employed in prior attempts to alleviate this problem. Ongoing efforts continue to channel the maximum possible amount of heat, which has been generated in the combustion chambers, from the exhaust ports of the cylinder heads into and through the exhaust system, minimizing the amount which is released in the engine compartment.
Another important reason for wishing to channel the maximum amount of heat possible through the exhaust system is that by retaining heat in the exhaust system, "light off" of the catalytic converter may be achieved sooner if more heat is conveyed directly to the converter rather than dissipated outwardly. This promotes greater fuel efficiency as well as lowered exhaust emissions, which are both high priorities in today's market.
For all of the above listed reasons, it is desirable to retain heat within components which contact engine exhaust.